Iliac extension with flared cuff

ABSTRACT

A leg extension ( 10 ) for a stent grafting system to connect between an aortic graft and an iliac graft. The leg extension is a tubular body ( 12 ) of a biocompatible graft material with self-expanding stents connected along the length of the tubular body and the tubular body having a distal end with a connection region. The connection region has a flared stent defining an external frusto-conical surface to provide a connection arrangement to engage within an internally flared portion of an iliac graft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of provisional application Ser. No.60/838,963, filed Aug. 18, 2006.

INCORPORATION BY REFERENCE

The following co-pending patent applications are referred to in thefollowing description:

PCT Patent Publication No. WO 98/53761 entitled “A Prosthesis and aMethod Deploying a Prosthesis”

U.S. Provisional Patent Application Ser. No. 60/686,252, entitled “IliacArtery Stent Graft” and U.S. Non-Provisional patent application Ser. No.11/444,688 and Publication No. US-2006-0287704-A1.

U.S. Provisional Patent Application Ser. No. 60/838,776 filed on Aug.18, 2006 herewith and entitled “Configuration of Branched Stent Grafts”

U.S. Patent Application Publication No. US-2003-01 99967-A1, and PCTPatent Publication No. WO 2003-0821 53 entitled “Bifurcated BranchVessel Prosthesis”

U.S. Patent Application Publication No. US-2004-0082990-A1, and PCTPatent Publication No. WO 2004101 7867 entitled “Composite Prostheses”

U.S. Pat. No. 6,695,875 entitled “Endovascular Stent Graft”

TECHNICAL FIELD

This invention relates to a medical device and more particularly to amedical device for use in relation to endovascular surgery.

BACKGROUND OF THE INVENTION

There have been used bifurcated stent grafts for treating abdominalaortic aneurysms. Such stent grafts include a tubular body to extend inthe aorta towards the renal arteries of a patient and usually a shorterleg and a longer leg with, once the bifurcated graft is deployed, anextension leg provided to extend down one iliac artery from the shorterleg with the longer leg extending down the other iliac artery.

In some cases of aneurysm, however, the aneurysm extends beyond theaortic bifurcation and down one at least of the iliac arteries. In suchcases a separate branched iliac stent graft is deployed in the commoniliac artery to allow for blood flow into the internal iliac and downthe external iliac artery from the common iliac artery. There remains,however, the problem of connecting this branched iliac stent graft withthe bifurcated stent graft in the aortic region.

It is to provide an extension for such an arrangement that the presentinvention is directed.

A particular problem with stent grafting in the common iliac region isthat there is only a relatively short distance distally of the aorticbifurcation in which to make a connection and it is desirable that assecure as possible connection is provided.

Branched iliac stent grafts for use with the present invention aredescribed in two U.S. Provisional Patent Applications. U.S. ProvisionalPatent Application Ser. No. 60/686,252, filed Jun. 1, 2005 entitled“Iliac Artery Stent Graft” discloses a side branch stent graft having amain tubular body and a tubular side branch that is affixed into themain tubular so that the lumen of the side branch is in fluidcommunication with the lumen of the main body. External zig-zag stentsare on the main body proximal and distal the side branch. At least oneinternal zig-zag stent is at the distal end of the main body. Areinforcing ring is around the proximal end of the main body andstitched thereto. This feature and other features disclosed in U.S.Provisional Patent Application Ser. No. 60/686,252 could be used withthe present invention, and the disclosure of U.S. Provisional PatentApplication Ser. No. 60/686,252 is herewith incorporated in its entirelyinto this specification.

U.S. Provisional Patent Application Ser. No. 60/838,776 filed on Aug.18, 2006 herewith and entitled “Configuration of Branched Stent Grafts”discloses a stent graft with at least two adjacent fenestrations in atubular body. A tube extends into the body from each of the at least twofenestrations. The tubes are joined and open into a single larger tubewithin the tubular body. The teaching of this patent specification isincorporated in the present application in its entirety.

Typical branched aortic bifurcation stent grafts are described in PCTPatent Publication No. WO 98153761 entitled “A Prosthesis And A Methodand Means of Deploying A Prosthesis” discloses an introducer for aprosthesis which retains the prosthesis so that each end can be movedindependently. These features and other features disclosed in PCT PatentPublication No. WO 98153761 could be used with the present invention andthe disclosure of PCT Patent Publication No. WO 981 53761 is herewithincorporated in its entirety into this specification.

U.S. patent application Ser. No. 10/396,676, filed Mar. 25, 2003, andpublished on Oct. 23, 2003, as U.S. Patent Application Publication No.US-2003-01 99967-A1, and PCT Patent Publication No. WO 2003-0821 53entitled “Bifurcated Branch Vessel Prosthesis” disclose a stent graftwith a fenestration in the tubular wall thereof. A tube extends from thefenestration into the main lumen and is in fluid communicationtherewith. An extension leg stent graft can be deployed from a branchvessel into the fenestration to seal in the tube. A flared guideassociated with the fenestration can be provided interiorly orexteriorly. This feature and other features disclosed in U.S. PatentApplication Publication No. US-2003-0199967-A1, and PCT PatentPublication No. WO 2003-0821 53 could be used with the presentinvention, and the disclosure of U.S. Patent Application Publication No.US-2003-01 99967-A1, and PCT Patent Publication No. WO 2003-0821 53 isherewith incorporated in its entirety into this specification.

U.S. Provisional Patent Application Ser. No. 60/405,769, filed Aug. 23,2002, U.S. patent application Ser. No. 10/645,095, filed Aug. 23, 2003,and published on Apr. 29, 2004, as U.S. Patent Application PublicationNo. US-2004-0082990-A1, and PCT Patent Publication No. WO 2004101 7867entitled “Composite Prostheses” disclosed prostheses or stent graftssuitable for endoluminal deployment. These prostheses and other featuresdisclosed in U.S. Provisional Patent Application Ser. No. 60/405,769,U.S. patent application Ser. No. 10/645,095, and U.S. Patent ApplicationPublication No. US-2004-0082990-A1, and PCT Patent Publication No. WO20041077867 could be used with the present invention and the disclosureof U.S. Provisional Patent Application Ser. No. 60/405,769, U.S. patentapplication Ser. No. 10/645,095, and U.S. Patent Application PublicationNo. US-2004-0082990-A1, and PCT Patent Publication No. WO 2004/017867 isherewith incorporated in its entirely into this specification.

U.S. Pat. No. 6,695,875 entitled “Endovascular Stent Graft” discloses amain stent graft body and a separate attachment graft tube that extendsproximally therefrom. The attachment graft tube has a proximalattachment stent for infrarenal attachment of the assembly to the aorta.These features and other features disclosed in U.S. Pat. No. 6,695,875could be used with the resent invention and the disclosure of U.S. Pat.No. 6,695,875 is herewith incorporated in its entirety into thisspecification.

Throughout this specification the term distal with respect to a portionof the aorta, a deployment device or a prosthesis means the end of theaorta, deployment device or prosthesis further away in the direction ofblood flow away from the heart and the term proximal means the portionof the aorta, deployment device or end of the prosthesis nearer to theheart. When applied to other vessels similar terms such as caudal andcranial should be understood.

SUMMARY OF THE INVENTION

In one form therefore, although this may not necessarily be the broadestor only form, the invention is said to reside in a leg extension for astent grafting system, the leg extension comprising a tubular body of abiocompatible graft material, the tubular body having a proximal endwith an outside sealing surface, a plurality of self-expanding stentsconnected to the tubular body along the length thereof with at least oneself-expanding stent within the tubular body at the proximal end and thetubular body having a distal end with a connection region, theconnection region comprising a flared stent defining an externalfrusto-conical surface extending therefrom whereby to provide aconnection arrangement to engage within an internally flared portion ofan iliac graft, whereby the leg extension can connect between apre-deployed branched iliac stent graft to a pre-deployed aorticbifurcation stent graft.

It will be seen that by this invention, there is provided an iliacextension stent graft which at its distal end can connect into aninternally flared portion of a pre-deployed branched iliac graft and atits proximal end can extend up into a leg of a bifurcated aortic stentgraft. By providing the proximal end with the outside sealing surfacethe proximal end of the stent graft can be variably positioned into theleg of a bifurcated stent graft to provide the required fluid connectionbetween the pre-deployed branched iliac stent graft to the pre-deployedaortic bifurcation stent graft.

The flared stent is preferably a zigzag style Gianturco stent which maybe formed from stainless steel, Nitinol or other suitable materials.

The flared stent can in one embodiment be formed as self expanding stentcomprising a resilient wire, the resilient wire comprising a pluralityof struts and a bend between each strut, the stent as formed beingsubstantially planar and in use being able to be formed into asubstantially flared form with at least the first strut and the laststrut overlapping.

Alternatively the flared stent can be formed from a resilient wirecomprising a plurality of struts and a bend between each strut, thestent as formed being in a substantially planar form and the ends joinedby welding or other technique.

In one form of the invention, the flared stent may be a bare stentextending from the distal end of the tubular body.

Alternatively the flared stent can be a covered stent comprising a coverof a biocompatible material.

In one form, the cover may be stitched along at least part of the lineof the wire of the zigzag stent to in effect form a series of petalsflaring out from the tubular body or the cover may extend between all orsome of the distal bends of the flared stent.

There can be further included a ring stent at the distal end of theconnection region fastened to the distal bends of the flared stentand/or to the cover of the connection region.

The proximal region with the outside sealing surface may be of a lengthof one, two or more stents within the tubular body. Similarly the distalsealing region may be of a length of one, two or more stents within thetubular body.

The biocompatible material from which the tubular body and the cover ofthe connection region is formed is preferably non-porous so that it doesnot leak or sweat under physiologic forces. The graft material ispreferably made of woven or knitted polyester (Vascutek Ltd.,Renfrewshire, Scotland, UK). Other biocompatible fabrics, non-wovenmaterials and porous sheets may be used as the graft material. Examplesof biocompatible polymers from which porous sheets can be formed includepolyesters, such as poly(ethylene terephthalate), polylactide,polyglycolide and copolymers thereof; fluorinated polymers, such asPTFE, expanded PTFE and poly(vinylidene fluoride); polysiloxanes,including polydimethyl siloxane; and polyurethanes, includingpolyetherurethanes, polyurethane ureas, polyetherurethane ureas,polyurethanes containing carbonate linkages and polyurethanes containingsiloxane segments. In addition, materials that are not inherentlybiocompatible may be subjected to surface modifications in order torender the materials biocompatible. Examples of surface modificationsinclude graft polymerization of biocompatible polymers from the materialsurface, coating of the surface with a crosslinked biocompatiblepolymer, chemical modification with biocompatible functional groups, andimmobilization of a compatibilizing agent such as heparin or othersubstances. Thus, any polymer that may be formed into a porous sheet canbe used to make a graft material, provided the final porous material isbiocompatible. Polymers that can be formed into a porous sheet includepolyolefins, polyacrylonitrile, nylons, polyaramids and polysulfones, inaddition to polyesters, fluorinated polymers, polysiloxanes andpolyurethanes as listed above. Preferably the porous sheet is made ofone or more polymers that do not require treatment or modification to bebiocompatible. The graft material may include a biocompatiblepolyurethane. Examples of biocompatible polyurethanes include THORALON®(Thoratec, Pleasanton, Calif.), BIOSPAN®, BIONATE®, ELASTHANE™, PURSIL™and CARBOSIL™ (Polymer Technology Group, Berkeley, Calif.). As describedin U.S. Patent Application Publication No. 2002/0065552 A1, incorporatedherein by reference, THORALON® is a polyetherurethane urea blended witha siloxane-containing surface modifying additive. Specifically, thepolymer is a mixture of base polymer BPS-215 and an additive SMA-300.The graft material may also include extracellular matrix materials. The“extracellular matrix” is a collagen-rich substance that is found inbetween cells in animal tissue and serves as a structural element intissues. It is typically a complex mixture of polysaccharides andproteins secreted by cells. The extracellular matrix can be isolated andtreated in a variety of ways. Following isolation and treatment, it isreferred to as an “extracellular matrix material,” or ECMM. ECMMs may beisolated from submucosa (including small intestine submucosa), stomachsubmucosa, urinary bladder submucosa, tissue mucosa, renal capsule, duramater, liver basement membrane, pericardium or other tissues. Purifiedtela submucosa, a preferred type of ECMM, has been previously describedin U.S. Pat. Nos. 6,206,931, 6,358,284 and 6,666,892 as abio-compatible, non-thrombogenic material that enhances the repair ofdamaged or diseased host tissues. U.S. Pat. Nos. 6,206,931, 6,358,284and 6,666,892 are incorporated herein by reference. Purified submucosaextracted from the small intestine (“small intestine submucosa” or“SIS”) is a more preferred type of ECMM for use in this invention.Another type of ECMM, isolated from liver basement membrane, isdescribed in U.S. Pat. No. 6,379,710, which is incorporated herein byreference. ECMM may also be isolated from pericardium, as described inU.S. Pat. No. 4,502,159, which is also incorporated herein by reference.Irrespective of the origin of the graft material, the graft material canbe made thicker by making multi-laminate constructs, for example SISconstructs as described in U.S. Pat. Nos. 5,968,096; 5,955,110;5,885,619; and 5,711,969. All of these references are incorporatedherein by reference.

Throughout this specification the term distal with respect to a portionof the aorta, a deployment device or a prosthesis is the end of theaorta, deployment device or prosthesis further away in the direction ofblood flow away from the heart and the term proximal means the portionof the aorta, deployment device or end of the prosthesis nearer to theheart. When applied to other vessels similar terms such as caudal andcranial should be understood.

BRIEF DESCRIPTION OF THE DRAWING

This then generally describes the invention but to assist withunderstanding, reference will now be made to the accompanying drawingswhich show preferred embodiments of the invention.

In the drawings:

FIG. 1 shows a first embodiment of leg extension for a stent graftingsystem according to the present invention;

FIG. 2 shows a further embodiment of a leg extension for a stentgrafting system according to the present invention;

FIG. 3 shows a still further embodiment of a leg extension for a stentgrafting system according to the present invention;

FIG. 3A shows detail of the flared stent of the embodiment of FIG. 3 ina laid flat configuration;

FIG. 3B shows detail of the flared stent of the embodiment of FIG. 3 ina frusto-conical configuration;

FIG. 4 shows a still further embodiment of a leg extension for a stentgrafting system according to the present invention;

FIG. 5A shows an alternative embodiment of a leg extension for a stentgrafting system according to the present invention;

FIG. 5B shows a form of flared stent useful for the connection region ofthe present invention and in particular the embodiment shown in FIG. 5A;

FIG. 6 shows an alternative embodiment of a leg extension for a stentgrafting system according to the present invention;

FIG. 7 shows an outside view of a connection between a branched iliacstent graft and a leg extension for a stent grafting system according toone embodiment of the invention;

FIG. 8 shows a longitudinal cross sectional view of the connectedcomponents shown in FIG. 7; and

FIG. 9 shows a schematic view of a stent grafting system incorporating aleg extension according to the present invention assembled within thevasculature of a patient.

DETAILED DESCRIPTION

Now looking more closely at the drawings and more particularly FIG. 1 itwill be seen that a first embodiment of leg extension 10 for a stentgrafting system according to the present invention comprises a tubularbody 12 of a biocompatible graft material with the tubular bodysupported by self expanding stents 15. A connection region 14 comprisinga flared stent 16 in this embodiment covered by a graft material cover18 is at the distal end 24 of the leg extension 10.

The tubular body has a external proximal sealing surface 20 at itsproximal end 22. The external proximal sealing surface has selfexpanding stents within the tubular body. The distal end 24 also has asealing surface 26. The distal sealing surface has self expanding stentswithin the tubular body. The external proximal sealing surface 20 isarranged to seal within the leg of a bifurcated stent graft and thedistal sealing surface 26 is adapted to seal within the proximal end ofa branched iliac stent graft as will be discussed later.

Although the leg extension 10 has been shown as a particular length thelength may vary and hence the number of intermediate stents 12 and thelength of the tubular body can vary. There may be one, two or more selfexpanding stents within the sealing regions 20 and 26 and one, two ormore self expanding stents 15 outside the tubular body 1 between thesealing regions 20 and 26.

FIG. 2 shows an alternative embodiment according to the presentinvention in which the leg extension 30 is substantially similar to thatshown in FIG. 1 except that at the distal end 32 of the connectionportion 18 there is a resilient ring 34 formed from a shape memory metalsuch as a nickel alloy Nitinol™ stitched to the cover 18 by stitching 36as well as being attached to the distal bends 33 of the flared stent 16.The resilient ring 34 assists in maintaining the flare in the connectionportion and hence maintaining a connection as discussed above.

FIG. 3 shows a still further embodiment of a leg extension according tothe present invention. In this embodiment the leg extension 40 comprisesa tubular body 42 of a biocompatible graft material with an uncoveredstent 44 providing the connection region 46. The uncovered stent 44 is aself expanding stent formed into a zig zag frusto conical configurationand is connected by the bends at the narrower end 43 of the stent to oneend of the tubular body 42 such that it forms the flared configurationto comprise the connection region 46.

FIG. 3A shows detail of the flared stent of the embodiment of FIG. 3 ina laid flat configuration and FIG. 3B shows detail of the flared stentof the embodiment of FIG. 3 in a frusto-conical configuration. In thisembodiment the stent 44 comprises struts 47, proximal bends 48 a anddistal bends 48 b between the struts. The stent is initially formed intoa flat configuration from a shape memory metal wire as shown in FIG. 3Aand then after heat treatment is formed into a frusto-conical shape andhas a welded, adhered or crimped scarf joint 49 to connect the ends ofthe wire into a continuous zig-zag shape.

FIG. 4 shows a still further embodiment of a leg extension according tothe present invention. The leg extension 50 has a tubular body 52 of abiocompatible graft material and the connection region 54 comprises azig zag stent 56 which is partially covered by a biocompatible graftmaterial 58. In this embodiment alternate gaps between pairs of adjacentstruts are left bare or uncovered.

FIG. 5A shows a still further embodiment of a stent graft according tothe present invention. In this embodiment the leg extension stent graft60 comprises a tubular body 62 of biocompatible graft material with afour lobed stent 64 fastened to the distal end 66. A covering of graftmaterial 68 is stitched along the struts of the four lobed stent 64 toprovide a petal effect. The stent 64 is a self expanding stent formedinto a zig zag configuration from a shape memory metal such as thenickel alloy Nitinol™.

FIG. 5B shows the form of stent according to the embodiment of theinvention shown in FIG. 5A. It will be seen that the stent 64 is formedfrom a single length of nitinol wire which commences at a loop 70adjacent a bend 70 a and forms a series of struts 74 with bends 76 inbetween them for two circuits before terminating at loop 72 adjacent tobend 72 a with an overlap of one extra strut. The Nitinol™ wire may be0.15 mm diameter. The Nitinol™ wire is formed into the four lobedfrusto-conical shape and then heat treated to memorise that shape.

FIG. 6 shows a still further embodiment of a leg extension according tothe present invention. In this embodiment the leg extension 61 comprisesa tubular body 63 of a biocompatible graft material with an uncoveredstent 65 providing the connection region 67. The uncovered stent 65 is aself expanding stent formed into a zig zag frusto conical configurationand is connected by the bends 69 at the narrower end of the stent to oneend of the tubular body 63 such that it forms the flared configurationto comprise the connection region 67. To assist the stent 65 to maintainthe flared configuration a ring 68 formed from a shape memory metal suchas a nickel alloy Nitinol™ stitched to the outer bends 69 a by stitching71.

FIG. 7 and FIG. 8 show one arrangement by which a leg extensionaccording to the present invention is connected into a branched iliacstent graft. The branched iliac stent graft 80 comprises a tubular body82 of a biocompatible graft material and a side arm 84 extending fromthe tubular body. At the proximal end of the tubular body is a ringreinforcement 86. The leg extension 10 of the type shown in FIG. 1extends into the lumen of the iliac graft 80 at the proximal end 81 ofthe branched iliac stent graft 80 and extends into the tubular body 82until the flared connection region 14 fits into the wider portion 90where the side arm 84 extends from the tubular body 82. With the flaredportion extending into the expanded portion 90 on the tubular body 82 agood connection between the two components is obtained which would bemore difficult to pull out.

FIG. 9 shows a schematic view of the vasculature of a patientparticularly showing the aorta and aortic bifurcation extending downtowards the iliac arteries. The vasculature comprises an aorta 100 inthe region between the renal arteries 102 and the aortic bifurcation104. Common iliac arteries 106 and 108 extend from the aorticbifurcation 104. The common iliac arteries 106 and 108 each bifurcateinto internal iliac arteries 110 and 11 and external iliac arteries 114and 116 respectively. The aorta 100 has an aneurysm 118 which alsoextends down the common iliac artery 106 towards the iliac bifurcation117.

To traverse the aneurysm a bifurcated aortic stent graft 10 has beendeployed into the aorta 100. The proximal end 12 of the bifurcated stentgraft 120 is engaged onto a non-aneurysed portion 14 of the aorta justdistal of the renal arteries. To ensure good fixation the stent graft 10includes a supra renal exposed stent 16 with barbs 18 engaging the wallof the aorta proximal of the renal arteries 102.

The stent graft 10 has a short leg 130 and a long leg 132 extending froma bifurcation 134 at its distal end 136. The long leg 132 has a sealingsurface 138 at its distal end and this engages in a sealing manner intoan non-aneurysed portion of the common iliac artery 108.

The aneurysm in the common iliac artery 106 requires the placement of aniliac stent graft 140 with a branch 142 from which a covered extensionpiece 144 can extend down the internal iliac artery 110. The distal end148 of the iliac stent graft 140 engages in a sealing manner into annon-aneurysed portion of the external iliac artery 114.

The short leg 130 does not extend down to the aortic bifurcation andhence it is necessary to provide an iliac extension piece 150 which goesbetween the short leg 130 of the bifurcated aortic stent graft 10 andthe proximal end 152 of the iliac stent graft 140. It is to theconfiguration of this iliac extension piece 150 that the presentinvention is directed.

The iliac extension piece 150 can be any of the embodiments shown inFIGS. 1 to 6 depending upon the requirements of a particular situation.The leg extension 150 extends into the lumen of the branched iliac graft140 at the proximal end 152 of the branched iliac stent graft 140 andextends into the tubular body thereof until its flared connection regionfits into the wider portion of the branched iliac stent graft where theside arm 142 extends from the tubular body. With the flared portionextending into the expanded portion on the tubular body a goodconnection between the two components is obtained even though there is arelatively short overlap.

In practice the order of placement of the various components of thestent grafting system in the case where there is an aneurysm whichextends down into one of the common iliac arteries is as follows:

Deploy the branched iliac stent graft.

Deploy the internal iliac extension.

Deploy the bifurcated aortic stent graft.

Deploy the iliac extension piece according to the present invention.

Throughout this specification various indications have been given as tothe scope of this invention but the invention is not limited to any oneof these but may reside in two or more of these combined together. Theexamples are given for illustration only and not for limitation.

Throughout this specification and the claims that follow unless thecontext requires otherwise, the words ‘comprise’ and ‘include’ andvariations such as ‘comprising’ and ‘including’ will be understood toimply the inclusion of a stated integer or group of integers but not theexclusion of any other integer or group of integers.

1. A leg extension stent graft for a stent grafting system, the legextension stent graft comprising a tubular body of a biocompatible graftmaterial, the tubular body having a proximal end with an outside sealingsurface, a plurality of self-expanding stents connected to the tubularbody along the length thereof with at least one self-expanding stentwithin the tubular body at the proximal end and the tubular body havinga distal end with a connection region, the connection region comprisinga flared stent defining an external frusto-conical surface extendingfrom the distal end of the tubular body whereby to provide a connectionarrangement to engage within an internally flared portion of an iliacgraft, whereby the leg extension can connect between a pre-deployedbranched iliac stent graft to a pre-deployed aortic bifurcation stentgraft.
 2. A leg extension stent graft as in claim 1 wherein the flaredstent is a zigzag style Gianturco stent
 3. A leg extension stent graftas in claim 1 wherein the flared stent is formed from a materialselected from the group comprising stainless steel and Nitinol.
 4. A legextension stent graft as in claim 1 wherein the flared stent is a selfexpanding stent comprising a resilient wire, the resilient wirecomprising a plurality of struts and a bend between each strut, thestent, as formed, being substantially planar and in use being able to beformed into a substantially flared form with at least the first strutand the last strut overlapping.
 5. A leg extension stent graft as inclaim 1 wherein the flared stent is a self expanding stent comprising aresilient wire, the resilient wire comprising a plurality of struts anda bend between each strut, the stent as formed being in a substantiallyplanar form and the ends joined by welding or other technique.
 6. A legextension stent graft as in claim 1 wherein the flared stent is a barestent extending from the distal end of the tubular body.
 7. A legextension stent graft as in claim 1 wherein the flared stent is a selfexpanding stent comprising a resilient wire, and further comprising afrusto-conical cover of a biocompatible graft material.
 8. A legextension stent graft as in claim 7 wherein the cover is stitched alongat least part of the line of the wire of stent to in effect form aseries of petals flaring out from the tubular body.
 9. A leg extensionstent graft as in claim 7 wherein the cover is stitched along at leastpart of the line of the wire of stent to in effect form a series ofpetals flaring out from the tubular body and the cover extends betweensome of the distal bends of the flared stent.
 10. A leg extension stentgraft as in claim 1 wherein the flared stent is a self expanding stentcomprising a resilient wire, the resilient wire comprising a pluralityof struts and a distal bend between each strut at a distal end of theflared stent and further including a ring stent at the distal end of theconnection region fastened to the distal bends of the flared stent. 11.A leg extension stent graft as in claim 10 wherein the flared stentcomprises a frusto-conical cover of a biocompatible graft material and adistal end of the frusto-conical cover is stitched to the ring stent.12. A leg extension stent graft for a stent grafting system, the legextension leg extension stent graft comprising a tubular body of abiocompatible graft material, the tubular body having a proximal endwith an outside sealing surface, a plurality of self-expanding stentsconnected to the tubular body along the length thereof with at least oneself-expanding stent within the tubular body at the proximal end and thetubular body having a distal end with a connection region, theconnection region comprising a flared self expanding stent comprising aresilient wire, the resilient wire comprising a plurality of struts anda distal bend between each strut at a distal end of the flared stent andfurther including a ring stent at the distal end of the connectionregion fastened to the distal bends of the flared stent and furthercomprising a frusto-conical cover of a biocompatible graft material onthe flared self expanding stent thereby defining an externalfrusto-conical sealing surface extending therefrom whereby to provide aconnection and sealing arrangement to engage within an internally flaredportion of an iliac graft, whereby the leg extension can connect betweena pre-deployed branched iliac stent graft to a pre-deployed aorticbifurcation stent graft.